Wizard Sinterklaas is a wizard and librarian in the Wizards' Tower who first appeared in the 2011 Christmas event. Players need to speak to him in order to start the event. He is somewhat forgetful and isn't very sure about what he is supposed to be doing, something that is often criticised by the guests from the Magic Guild. During the 2016 Christmas event, Sinterklaas reprised the role he played in the 2011 event. His scene can be played after completion of the 2007 and 2010 events.

He is a reference to the Dutch and Belgian holiday named Sinterklaas, which is one of the sources of Santa Claus. Despite being similar to Santa Claus, Sinterklaas is celebrated on the evening of 5 (6 December in Belgium), and is unrelated to Christmas (except for the fact that Santa is derived from Sinterklaas). The reference is further supported by the fact that the wizard wears a red hat, similar to Sinterklaas's red mitre.

He claims to be librarian on the seventh floor of the tower, and that the tower is bigger from the inside for wizards than it is outside. This is a reference to the TARDIS from the television series Doctor Who, the machine which is larger on the inside.